Atomic force microscopes (AFM) are used to investigate surfaces on an atomic scale. As discussed in "Atomic Force Microscope," by G. Bining, J. C. F. Quate, and C. F. Gerber, as published in Physical Review Letters, Vol. 56, No. 9, Mar. 3, 1986, such microscopes operate by having a probe in contact with the surface to be profiled. As the probe is moved and the surface contour changes, the probe is electrically adjusted to keep the force constant. Monitoring the current or voltage applied to the probe to maintain the constant force will provide an accurate indication of the surface contour. Moving the probe in a series of adjacent scans across the surface will allow a three-dimensional contour map to be generated.
The AFM described by Bining, et al. can profile surfaces with forces sufficiently small that the surface is not deformed. Bining, et al. utilize a gold foil lever for holding a diamond tip that is scanned across the surface. A scanning tunnelling microscope (STM) is used to determine the position of the lever in order to allow adjustment of the tip force.
The heart of the AFM as described by Bining, et al. is the arrangement of the lever and diamond tip. That arrangement suffers from two inherent problems. The first is that a number of piezoelectric elements are necessary to move the tip. Second, the STM must be employed to determine the deflection of the lever and thus the force to be applied to the tip. Beyond being a complex arrangement, the STM is subject to lateral sensitivity, which results in topographic artifacts.
Accordingly, it is the principal object of the present invention to improve the performance and sensitivity of an ATM.
It is another object of the present invention to simplify the construction of an ATM.
Yet another object of the present invention is to minimize topographic artifacts in AFM images.